Two linked towers of offices and workspaces for Amsterdam's Water Control Board and Water Management and Sewerage Service occupy a strategic position on the River Amstel with a view across the water and the inner city. The required surface area on what is a limited footprint has been divided between two towers rather than restricted to a single volume. This gives the whole a transparency, together with multiple sight lines from the workplaces to the surroundings. The towers, joined in places by glass bridges, stand on a half-sunken plinth of parking places and work and reception rooms. The key communal spaces assemble on the ninth and tenth floors from where they look out over the city through large areas of glass. The supporting structure is a grid of steel columns.